scholarly journals The stimulation by synaptic transmitters of the incorporation of oleate into the phospholipid of synaptic membranes

1975 ◽  
Vol 148 (3) ◽  
pp. 557-565 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Initial Rate ◽  
Optimum Concentration ◽  
Synaptic Membranes ◽  
Gamma Aminobutyric Acid ◽  
Response Curves ◽  
Ethanolamine Glycerophospholipids ◽  
Sodium Phosphate Buffer ◽  
Choline Glycerophospholipids ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

Noradrenaline stimulated the incorporation of oleate into choline glycerophospholipids of guinea-pig brain synaptic membranes incubated in sodium phosphate buffer. In the presence of 1 mm-NaF, noradrenaline stimulated the incorporation of oleate into the choline glycerophospholipids, phosphatidylinositol, ethanolamine glycerophospholipids, phosphatidylserine and phosphatidic acid of synaptic membranes incubated in 10 mm-Tris-HCl buffer. In Tris-CHl containing 1 mm-NaF, stimulation of incorporation of oleate into choline glycerophospholipids by noradrenaline was enhanced by ATP, CaCl2, MgCl2 and CoA plus dithiothreitol. The optimum concentration of CaCl2 for stimulation by 10 mum-noradrenaline was 10 mum. In the presence of CaCl2, the optimum concentration of ATP-2MgCl2 was in the range 0.1-1 mm. Acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine, histamine and gamma-aminobutyric acid also stimulated the incorporation of oleate into choline glycerophospholipids of synaptic membranes. Sigmoidal dose-response curves were obtained, similar to those obtained previously for stimulation by the same agonists of the hydrolysis of phosphatidylcholine by phospholipase A2 (Gullis & Rowe, 1975a). The initial rate of transfer of oleate from oleoyl-CoA to choline glycerophospholipid was similar to the initial rate of transfer from oleate-albumin, stimulated by noradrenaline. Transfer of oleate from oleoyl-CoA was not appreciably stimulated by noradrenaline, but was stimulated by ATP and MgCl2.

scholarly journals The stimulation by transmitter substances and putative transmitter substances of the net activity of phospholipase A2 of synaptic membranes of cortex of guinea-pig brain

1975 ◽  
Vol 148 (2) ◽  
pp. 197-208 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Guinea Pig ◽  
Phospholipase A2 ◽  
Synaptic Vesicles ◽  
Optimum Concentration ◽  
Synaptic Membranes ◽  
Phospholipase A1 ◽  
Response Curves ◽  
Pig Brain ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

1. The distribution of the hydrolyses of phosphatidylcholine by phospholipase A2 and phospholipase A1, and the hydrolysis of lysophosphatidylcholine by lysophospholipase, in subcellular and subsynaptosomal fractions of cerebral cortices of guinea-pig brain, was determined. 2. Noradrenaline stimulated hydrolysis by phospholipase A2 in whole synaptosomes, synaptic membranes and fractions containing synaptic vesicles. 3. Stimulation of hydrolysis by phospholipase A2 in synaptic membranes by noradrenaline was enhanced by CaCl2, and by a mixture of ATP and MgCl2. The optimum concentration of CaCl2, in the presence of ATP and MgCl2, for stimulation by 10 muM-noradrenaline was in the range 1-10muM. The optimum concentration for ATP-2MgCl2 in the presence of 1 muM-CaCl2 was in the range 0.1-1mM. 4. Hydrolysis by phospholipase A2 of synaptic membranes was also stimulated by acetylcholine, carbamoylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine), histamine, psi-aminobutyric acid, glutamic acid and aspartic acid. With appropriate concentrations of cofactors, sigmoidal dose-response curves were obtained, half-maximum stimulations being obtained with concentrations of stimulant in the range 0.1-1muM. 5. Taurine also stimulated hydrolysis of phosphatidylcholine by phospholipase A2. There were only slight stimulations with methylamine, ethylenediamine or spermidine. No stimulation was obtained with glucagon.

scholarly journals Glyceride lipases in nerve endings of guinea-pig brain and their stimulation by noradrenaline, 5-hydroxytryptamine and adrenaline

1973 ◽  
Vol 132 (2) ◽  
pp. 233-248 ◽  
Author(s):  
O. S. Vyvoda ◽  
C. E. Rowe
Keyword(s):  
Guinea Pig ◽  
Synaptic Vesicles ◽  
Protein Concentration ◽  
Synaptic Membranes ◽  
Ph Optimum ◽  
Triglyceride Lipase ◽  
Monoglyceride Lipase ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Guinea Pig Brain

1. Combined guinea-pig cortex and cerebellum was shown to contain triglyceride lipase, diglyceride lipase and monoglyceride lipase, which were assayed by the release of [1-14C]palmitate from [1-14C]palmitoylglycerol esters. Triglyceride lipase and diglyceride lipase were found in all particulate fractions. 2. With osmotically ruptured synaptosomes the rates of release of palmitate from glyceryl tripalmitate and glyceryl dipalmitate were 7–25μmol/h per g of protein and 0.18–0.69mmol/h per g of protein respectively. The logarithm of the rate of hydrolysis of glyceryl monopalmitate increased linearly with the logarithm of protein concentration. The pH optima of triglyceride lipase and diglyceride lipase were between 7 and 8. The pH optimum for monoglyceride lipase was approx. 8. 3. Triglyceride lipase and diglyceride lipase of osmotically ruptured synaptosomes were stimulated by noradrenaline, 5-hydroxytryptamine and adrenaline. Triglyceride lipase of isolated synaptic membranes was stimulated by 0.01–1mm-noradrenaline. Aging of membranes at 0°C decreased activity, which could still be stimulated by noradrenaline. Diglyceride lipase of isolated membranes was stimulated by 1μm–1mm-noradrenaline. The activity of triglyceride lipase in isolated synaptic vesicles was diminished by 1mm-5-hydroxytryptamine.

scholarly journals The stimulation of the phospholipase A2-acylation system of synaptic membranes of brain by cyclic nucleotides

1975 ◽  
Vol 148 (3) ◽  
pp. 567-581 ◽  
Author(s):  
R J Gullis ◽  
C E Rowe
Keyword(s):  
Cyclic Amp ◽  
Phospholipase A2 ◽  
Cyclic Nucleotides ◽  
Membrane Lipid ◽  
Synaptic Membranes ◽  
Choline Glycerophospholipids ◽  
Hydrolysis Of ◽  
Cyclic Ump ◽  
Cyclic Cmp ◽  
Stimulation Of

Hydrolysis of phosphatidylcholine by phospholipase A2 of synaptic membranes i n Tris-CHl buffer was stimulated by cyclic AMP, cyclic GMP, cyclic CMP, cyclic UMP and adenosine (0.1 mm). In the presence of 1 mm-NaF and cofactors, the same cyclic nucleotides and adenosine (10 mm) stimulated the incorporation of added oleate into the choline glycerophospholipids of synaptic membranes. Cyclic AMP and noradrenaline stimulated the incorporation of added oleate into position 2 of choline glycerophospholipid. Stimulation of net acylation was increased by preincubation in conditions which stimulated hydrolysis of phosphatidylcholine. Cyclic AMP only slightly stimulated the transfer of oleate from oleoyl-CoA into choline glycerophospholipid. The optimum concentration of CaCl2 for the stimulation of hydrolysis by phospholipase A2 by cyclic AMP was 1 mum. Stimulation of the incorporation of added oleate was maximal in the CaCl2 concentration range 1 mum-1mm. MgCl2 also enhanced stimulations, maximum effects being obtained with concentrations of 10 mum and 0.5 mm for hydrolysis by phospholipase A2 and incorporation of added oleate respectively. ATP enhanced the stimulation of incorporation of oleate but had no effect on the cyclic nucleotide stimulation of hydrolysis of added phosphatidylcholine by phospholipase A2. Adenosine, guanosine, ADP and 5′-AMP (all at 1 mm) inhibited the stimulation of incorporation of oleate by cyclic nucleotides and inhibited the transfer of oleate from oleoyl-CoA to phospholipid. They did not inhibit the stimulation of hydrolysis of added phosphatidylcholine (by phospholipase A2) by cyclic nucleotides, but inhibited the stimulation by noradrenaline, acetylcholine, 5-hydroxytryptamine, dopamine (3,4-dihydroxyphenethylamine) and histamine. Preincubation of synaptic membranes in the water or buffer increased the net activity of phospholipase A2. Preincubation with a mixture of ATP and MgCl2 increased the initial rate of acylation of membrane lipid.

Potentiometric properties of trialkylammonium ion-exchangers

1980 ◽  
Vol 58 (14) ◽  
pp. 1412-1417 ◽  
Author(s):  
Michel Gérin ◽  
James Fresco
Keyword(s):  
Ion Exchange ◽  
Electrochemical Sensor ◽  
Exchange Constant ◽  
Membrane Material ◽  
Ion Exchangers ◽  
Response Curves ◽  
Hydrolysis Of

The potentiometric behaviour of nitrobenzene solutions of 21 trialkylammonium salts employed as membrane material has been investigated. Deviations from ideal Nernst response curves for chloride, bromide, iodide, and perchlorate sensors were explicable on the basis of partition and hydrolysis of the ion exchangers. Interference coefficients for the anion selective electrochemical sensor tridodecylammonium perchlorate could be related to the ion-exchange constant of the salt.

scholarly journals Influence of Water Activity on Protease Adsorbed on Biochar in Organic Solvents

2017 ◽  
Vol 6 (4) ◽  
pp. 96 ◽  
Author(s):  
Hidetaka Noritomi ◽  
Jumpei Nishigami ◽  
Nobuyuki Endo ◽  
Satoru Kato ◽  
Katsumi Uchiyama
Keyword(s):  
Thermal Stability ◽  
Catalytic Activity ◽  
Organic Solvents ◽  
Water Activity ◽  
Initial Rate ◽  
Butyl Ester ◽  
Nitrogen Atmosphere ◽  
Bamboo Charcoal ◽  
Influence Of Water ◽  
Hydrolysis Of

We have found that the organic solvent-resistance of Alpha-chymotrypsin (Alpha-CT) is enhanced by adsorbing Alpha-CT onto bamboo charcoal powder (BCP), which is obtained by pyrolyzing bamboo waste under nitrogen atmosphere, and is markedly dependent on the thermodynamic water activity (aw) in organic solvents. When BCP-adsorbed　Alpha-CT was immersed in acetonitrile at an appropriate water activity, it effectively enhanced the transesterification of N-acetyl-L-tyrosine ethyl ester (N-Ac-Tyr-OEt) with n-butanol (BuOH) to produce N-acetyl-L-tyrosine butyl ester (N-Ac-Tyr-OBu), compared to the hydrolysis of N-Ac-Tyr-OEt with water to give N-acetyl-L-tyrosine (N-Ac-Tyr-OH). When the water activity was 0.28, the initial rate of transesterification catalyzed by BCP-adsorbed Alpha-CT was about sixty times greater than that catalyzed by free Alpha-CT. Regarding the reaction selectivity which is defined as a ratio of the initial rate of transesterification to that of hydrolysis, BCP-adsorbed α-CT was much superior to free Alpha-CT. The catalytic activity of BCP-adsorbed Alpha-CT was markedly dependent on the reaction temperature. Furthermore, concerning the thermal stability at 50 oC, the half-life of BCP-adsorbed Alpha-CT exhibited 3.8-fold, compared to that of free Alpha-CT.

scholarly journals Validation of Metamizole, Thiamin and Pyridoxine Simultaneous Analysis Methods in Tablet Preparations Using HPLC

2018 ◽  
Vol 1 (1) ◽  
pp. 19
Author(s):  
Vevi Maritha ◽  
Lukman Labasy
Keyword(s):  
Mobile Phase ◽  
Hplc Analysis ◽  
Sodium Sulfite ◽  
Hplc Method ◽  
Optimum Concentration ◽  
Diode Array ◽  
Good Precision ◽  
Chromatographic System ◽  
Chromatographic Condition ◽  
Hydrolysis Of

The aim of the present study was to develop and validate HPLC method for the simultaneous assay of metamizole, thiamine and pyridoxine in tablet. Metamizole is a substance that is easily hydrolyzed in the precence of water and oxygen. To inhibit the hydrolysis of metamizole during sample preparation prior to HPLC analysis, sodium sulfite is added and its optimum concentration was investigated. The chromatographic system includes a RP C8(2) column (150x4.6 mm, 5 µm particle size) in conjunction with Photo Diode Array (PDA) detector. The optimal chromatographic condition was obtained using a mobile phase consisting of phosphate buffer 35mM pH 3.0: methanol (80:20), flowrate 1.0 ml/min, and 10 µl injection volume. The metamizole, thiamine and pyridoxine were detected at 275 nm and 361 nm for cyanocobalamin. The Hydrolysis of metamizole was successfully inhibited by adding solution containing 1.5 mg/mL sodium sulfite to solvent and 0.5 mg/mL sodium sulfite to mobile phase. The validation results indicate a good specificity and a linear detector responses with r>0.999. The accuracy (% recovery) for metamizole, thiamine and piridoxine were 100.26%; 99.09%; and 100.03%, respectively. The method yields good precision with RSD of metamizole, thiamine and pyridoxine were 2.0912%; 1.4489%; and 0.8418% respectively. In the robustness study, the small changes of mobile phase pH yielded unsymmetrical peaks and lower resolution. The validated method was successfully applied for simultaneous assay of metamizole, thiamine and pyridoxine in tablet. Keywords: validation; metamizole; thiamine; pyridoxine; hydrolysis of metamizole; HPLC

scholarly journals Influence of Me2SO and incubation time on papain activity studied using fluorogenic substrates.

2001 ◽  
Vol 48 (4) ◽  
pp. 995-1002 ◽  
Author(s):  
M Szabelski ◽  
K Stachowiak ◽  
W Wiczk
Keyword(s):  
Incubation Time ◽  
Active Sites ◽  
Initial Rate ◽  
Substrate Binding ◽  
Rapid Decrease ◽  
Fluorogenic Substrates ◽  
Binding Process ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Papain activity in a buffer containing Me2SO was studied using fluorogenic substrates. It was found that the number of active sites of papain decreases with increasing Me2SO concentration whereas the incubation time, in a buffer containing 3% Me2SO does not affect the number of active sites. However, an increase of papain incubation time in the buffer with 3% Me2SO decreased the initial rate of hydrolysis of Z-Phe-Arg-Amc as well as Dabcyl-Lys-Phe-Gly-Gly-Ala-Ala-Edans. Moreover, an increase of Me2SO concentration in working buffer decreased the initial rate of papain-catalysed hydrolysis of both substrates. A rapid decrease of the initial rate (by up to 30%) was observed between 1 and 2% Me2SO. Application of the Michaelis-Menten equation revealed that at the higher Me2SO concentrations the apparent values of k(cat)/Km decreased as a result of Km increase and kcat decrease. However, Me2SO changed the substrate binding process more effectively (Km) than the rate of catalysis k(cat).

scholarly journals The metabolism of neuropeptides. Neurokinin A (substance K) is a substrate for endopeptidase-24.11 but not for peptidyl dipeptidase A (angiotensin-converting enzyme)

1985 ◽  
Vol 231 (2) ◽  
pp. 357-361 ◽  
Author(s):  
N M Hooper ◽  
A J Kenny ◽  
A J Turner
Keyword(s):  
Substance P ◽  
Selective Inhibitor ◽  
Synaptic Membranes ◽  
Neurokinin A ◽  
Pig Kidney ◽  
Endopeptidase 24.11 ◽  
The Family ◽  
General Capacity ◽  
Substance K ◽  
Hydrolysis Of

Both endopeptidase-24.11 and peptidyl dipeptidase A have previously been shown to hydrolyse the neuropeptide substance P. The structurally related peptide neurokinin A is also shown to be hydrolysed by pig kidney endopeptidase-24.11. The identified products indicated hydrolysis at two sites, Ser5-Phe6 and Gly8-Leu9, consistent with the known specificity of the enzyme. The pattern of hydrolysis of neurokinin A by synaptic membranes prepared from pig striatum was similar to that observed with purified endopeptidase-24.11, and hydrolysis was substantially abolished by the selective inhibitor phosphoramidon. Peptidyl dipeptidase A purified from pig kidney was shown to hydrolyse substance P but not neurokinin A. It is concluded that endopeptidase-24.11 has the general capacity to hydrolyse and inactivate the family of tachykinin peptides, including substance P and neurokinin A.

scholarly journals HIDROLISIS RUMPUT LAUT (Glacilaria sp.) MENGGUNAKAN KATALIS ENZIM DAN ASAM UNTUK PEMBUATAN BIOETANOL

Jurnal Kimia ◽  
2016 ◽  
Author(s):  
Yohanes Armawan Sandi ◽  
Wiwik Susanah Rita ◽  
Yenni Ciawi
Keyword(s):  
Gas Chromatography ◽  
Hydrochloric Acid ◽  
Sulphuric Acid ◽  
Ethanol Concentration ◽  
Reducing Sugar ◽  
Optimum Concentration ◽  
Raw Material ◽  
Optimum Length ◽  
Hydrolysis Of

The aim of this research is to determine the effect of enzyme and acids concentration on the yield of glucose produced in the hydrolysis of Glacilaria sp. in the production of bioethanol. The concentrations of cellulase used were 200 units/mL, 400 units/mL, 600 units/mL, 800 units/mL and the concentration of sulphuric acid (H2SO4) and hydrochloric acid (HCl) used were 1%, 3%, 5%, 7% (w/v). The concentration of reduction sugar was determined using Anthrone and analyzed using UV-Vis spectrophotometry and the determination of ethanol concentration was carried out by using gas chromatography. The results showed that the contents of reducing sugar produced by sulphuric acid (H2SO4) hydrolysis were 26,19%; 36,69%; 41,40%; 45,0% (v/v), by hydrochloric acid (HCl) were 12,12%; 14,03%; 15,17%; 16,50% (v/v), and by cellulase enzyme were 46,15%; 46,73%; 47,68%; 48,25% (v/v). Optimum concentration of reducing sugar produced by hydrolysis using 800 units/mL cellulase was 48,25% (v/v). The optimum length of fermentation to produce bioethanol using Glacilaria sp. as raw material was 5 days. In the fermentation, inoculum with a concentrations of 5% and 10% (w/v) produced 0,85% and 1,51% (v/v) ethanol.

Differential effects of extra- and intracellular anions on GABA-activated currents in bullfrog sensory neurons

1989 ◽  
Vol 62 (6) ◽  
pp. 1388-1399 ◽  
Author(s):  
N. Akaike ◽  
N. Inomata ◽  
T. Yakushiji
Keyword(s):  
Sensory Neurons ◽  
Dose Response ◽  
Kinetic Properties ◽  
Gamma Aminobutyric Acid ◽  
Response Curves ◽  
Concentration Jump ◽  
Inward Currents ◽  
Selective Channel ◽  
Concentration Clamp Technique ◽  
Dose Response Curves

1. Kinetic properties of gamma-aminobutyric acid (GABA)-gated inward and outward anion currents were investigated in the frog sensory neurons perfused internally and externally with various anions with the use of a rapid concentration-jump (termed as 'concentration-clamp') technique. 2. Extracellular Br- [( Br-]o) shifted the dose-response curves of GABA-induced inward anion currents to the left without affecting the maximum values, whereas [Cl-]o, [I-]o, [No3-]o, [HCOO-]o, and [CH3COO-]o altered the rate of desensitization differently without shifting the GABA dose-response curves, indicating that the kinetics of desensitization phase are affected differently by various extracellular anions. 3. [CH3COO-]o suppressed the maximum current of the dose-response curve of the GABA-induced inward ICl without affecting Kd. 4. Both activation and desensitization phases of GABA-induced ICl consisted of fast and slow components, respectively. [Br-]o, [I-]o, and [NO3-]o significantly prolonged the slow desensitization component, whereas both [HCOO-]o and [CH3COO-]o shortened it. The fast desensitization and the fast and slow activation components were also affected by these foreign anions. 5. GABA dose-response curves of inward currents carried by various intracellular anions (Cl-, Br-, NO3-, I-, SCN-, HCOO-, F-, CH3COO-, CH3CH2COO-, BrO3-, and ClO3-) while keeping a constant [Cl-]o had a constant Kd value but different saturating maximum currents. There were no marked differences among their current kinetics except in the case of SCN-, indicating that the current kinetics is not affected by replacing intracellular Cl- [( Cl-]i) with various foreign anions. 6. The configuration and amplitude of GABA-gated outward anion currents at a constant [Cl-]i reflected the extracellular action of individual anions on the anion-binding site of GABA receptor associated with the anion-selective channel. 7. The relative conductances of the various anions, calculated from the maximum peak currents in dose-response curves of the GABA-induced inward anion currents at a constant [Cl-]o, was in the sequence: I- greater than Br- greater than or equal to NO3- greater than ClO3- greater than SCN- greater than or equal to Cl- greater than HCOO- greater than BrO3- greater than CH3COO- greater than F- greater than CH3CH2COO-.(ABSTRACT TRUNCATED AT 400 WORDS)

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